BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	c_custkey,
	c_name,
	sum(l_extendedprice * (1 - l_discount)) as revenue,
	c_acctbal,
	n_name,
	c_address,
	c_phone,
	c_comment
from
	customer,
	orders,
	lineitem,
	nation
where
	c_custkey = o_custkey
	and l_orderkey = o_orderkey
	and o_orderdate >= date '1995-01-01'
	and o_orderdate < cast(date '1995-01-01' + interval '3 month' as date)
	and l_returnflag = 'R'
	and c_nationkey = n_nationkey
group by
	c_custkey,
	c_name,
	c_acctbal,
	c_phone,
	n_name,
	c_address,
	c_comment
order by
	revenue desc
LIMIT 20;
                                                                                                QUERY PLAN                                                                                                 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=1184498.75..1184498.80 rows=20 width=176) (actual time=43902.853..43902.862 rows=20 loops=1)
   Buffers: shared hit=907985 read=515100 dirtied=132 written=8085
   ->  Sort  (cost=1184498.75..1185887.44 rows=555474 width=176) (actual time=43902.849..43902.854 rows=20 loops=1)
         Sort Key: (sum((lineitem.l_extendedprice * (1::double precision - lineitem.l_discount))))
         Sort Method: top-N heapsort  Memory: 30kB
         Buffers: shared hit=907985 read=515100 dirtied=132 written=8085
         ->  HashAggregate  (cost=1164163.05..1169717.79 rows=555474 width=176) (actual time=43425.590..43755.473 rows=354618 loops=1)
               Buffers: shared hit=907982 read=515100 dirtied=132 written=8085
               ->  Hash Join  (cost=397626.69..1150276.20 rows=555474 width=176) (actual time=7297.711..40011.586 rows=940753 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=907982 read=515100 dirtied=132 written=8085
                     ->  Hash Join  (cost=397625.13..1142636.87 rows=555474 width=154) (actual time=7297.662..39346.515 rows=940753 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=907981 read=515100 dirtied=132 written=8085
                           ->  Merge Join  (cost=328597.13..1062499.39 rows=555474 width=12) (actual time=3150.168..32407.275 rows=940753 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=901777 read=486026 dirtied=132 written=8085
                                 ->  Sort  (cost=328597.12..330002.96 rows=562337 width=8) (actual time=3149.577..3359.003 rows=561506 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50897kB
                                       Buffers: shared hit=225348 read=4218 dirtied=17
                                       ->  Bitmap Heap Scan on orders  (cost=11921.85..274890.91 rows=562337 width=8) (actual time=487.855..2866.051 rows=561506 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Buffers: shared hit=225348 read=4218 dirtied=17
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11781.27 rows=562337 width=0) (actual time=349.985..349.985 rows=564369 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared read=1542
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688308.48 rows=14890948 width=12) (actual time=0.107..25484.551 rows=14808719 loops=1)
                                       Buffers: shared hit=676429 read=481808 dirtied=115 written=8085
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=4145.250..4145.250 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=6204 read=29074
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.017..1556.007 rows=1500000 loops=1)
                                       Buffers: shared hit=6204 read=29074
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.009..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 43999.917 ms
(40 rows)

COMMIT;
COMMIT